This invention relates to antennas and, in particular, to an antenna having elements thermally transferred to a dielectric sheet.
A variety of antennas are known in the art that use planar conductive elements; e.g. planar, phased array antennas, U.S. Pat. No. 3,587,110 (Woodward); spiral antennas, U.S. Pat. No. 3,509,465 (Andre et al.); a cavity combined with a spiral antenna U.S. Pat. No. 3,441,937 (Clasby et al.), and dipole arrays, U.S. Pat. No. 6,731,248 (Killen et al.). Another pattern of conductive elements is a fractal antenna; e.g. U.S. Pat. No. 6,104,349 (Cohen). Typically, the conductive elements of the antenna are produced by applying a conductive layer to a substrate and then patterning the layer; e.g., U.S. Pat. No. 6,731,248.
At ultra high frequencies, approximately 12 GHz, the wavelength is approximately 2.50 cm, which means that even seemingly small changes in dimension can be substantial fractions of a wavelength. Patterning conductive layers can be controlled to small fractions of a centimeter but the process for forming the conductive layers is expensive, uses solvents or other chemicals that must be disposed of properly, and is ill suited to making small quantities or experimental samples.
It is known in the art to use a plurality of thermal pins in an array for printing; e.g. see U.S. Pat. No. 3,855,448 (Hanagata et al.). It is also known in the art to thermally print electrically conductive carbon black from a ribbon; e.g. see U.S. Pat. No. 4,269,892 (Shattuck et al.).
In view of the foregoing, it is therefore an object of the invention to provide an antenna that is made by thermally bonding elements to a dielectric sheet.
Another object of the invention is to provide an antenna that can be changed easily for prototype or low volume production.
A further object of the invention is to provide an antenna in which an element is thermally bonded to a dielectric sheet by toner powder.